Abstract: The warm-up time of a glow plug starting device in a diesel engine is reduced by using as the material for the heat generating element in the glow plug a metallic resistance material whose resistance up to the starting temperature is less than two-thirds of the rated resistance of a conventional element. The starter circuit includes a detecting resistor in series with the heating element and a divider which divides the voltage across the heating element by the voltage across the detecting resistor in order to accurately determine the resistance and, thus, the temperature, of the heating element. The current to the element is interrupted and a self-holding starting relay is energized when the starting temperature has been obtained.

Abstract: A parallel circuit of an ordinary resistor exhibiting an ordinary resistance characteristic and a starting resistor abruptly increasing its resistance at a certain temperature is inserted between glow plugs in a Diesel engine and a battery. The resistance of the starting resistor is smaller than that of the ordinary resistor at a normal temperature. The resistance of the starting resistor becomes larger than that of the ordinary resistor when a large amount of current flows through the starting resistor. Therefore, current flows from the battery to the glow plugs mainly through the starting resistor at first, and then it flows mainly through the ordinary resistor. A voltage drop of the battery due to engine starting is prevented by bypassing the parallel circuit by a resistor. Preferably, the starting resistor is of honeycomb shape.

Abstract: A control for modulating the duty cycle of diesel engine glow plugs has two heat sensitive, normally closed switches each thermally coupled to a respective positive temperature coefficient (PTC) of resistivity heater in turn thermally coupled to a common heat sink. The heat sensitive switches are serially connected to each other, to an ignition switch and to a glow plug relay. The PTC heaters are connected to a point between the heat sensitive switches and the relay and to ground. A third PTC heater is disposed on the heat sink intermediate the first and second heaters and thermally coupled to the heat sink. The third heater is connected to an alternator and serves to cut off power to the glow plugs after a selected after glow stage. The two heat sensitive switches can be selected to open at approximately the same temperature for a random operating mode or at slightly different temperatures for a sequential operating mode.

Abstract: Switch-controlled apparatus for actuating a power switch to enable application of power from an associated power supply to a heater filament of a glow plug in a diesel engine is disclosed. The filament is one which is heated to a predetermined design temperature when a specified voltage is applied thereto. The power source has a supply voltage greater than the specified voltage of the filament. A switch accessible to an operator of the engine is operable in a first position to prevent the application of the supply voltage to the apparatus, operable in a second position to apply the supply voltage through a first terminal of the apparatus, and operable in a third position to apply the supply voltage through the first terminal and through a second terminal of the apparatus and to a starter for the engine.

Abstract: A starting aid for a diesel engine comprises a tubular member which in use extends into a combustion space of the engine, a spirally coiled heating element which is located in the end of the tube and which at its inner end is connected to a conductive rod. The outer end of the element is connected to a length of conductive tape extending substantially normal to the plane of the heating element. The tape at its other end is electrically connected to the tubular member. Conveniently the length of tape is formed as an extension of the tape forming the heating element this tape being folded so that the length of tape extends as described.

Abstract: To rapidly heat glow plugs having positive temperature coefficient characteristics, or glow plugs in circuit with a positive temperature coefficient resistor, without overloading connecting relay contacts, a current limiting resistor is placed in circuit with the glow plugs upon first connection thereof to a supply source. After elapse of a first time interval of about 0.1 to 0.3, maximally 1 second, a second switch is controlled to short-circuit the current limiting resistor to permit full voltage to be applied to the glow plugs for rapid heating thereof, during a second time interval, for example between about 2 to 6 seconds, the positive temperature characteristics of the circuit self-limiting current through the resistors to thereby protect circuit switches and relay contacts.

Abstract: A sheathed electric heater for use as an engine glow plug or the like is formed by providing a closed end metal sheath, installing a centered electric heating element that approaches the sheath closed end, adding a small amount of sinterable metal powder covering the end of the heating element at the closed end of the sheath, filling the remaining volume around the element with granular electrical insulating material, swaging the assembly to reduce its diameter, extend its length and compact the insulation, and sintering the metal powder by passing electric current therethrough to provide a low resistance electrical connection between the heating coil and the closed end of the sheath.

Abstract: A device for enhancing the starting of a diesel engine in which the current flow to the glow plugs of the engine during the warm-up time is controlled so as to heat the engine as quickly as possible without damage to the glow plugs. Each glow plug is connected in series with a low value resistance between an output terminal of the relay and one of the battery terminals. Also connected across the output terminal of the relay and the output battery terminal is a series combination of three resistors one of which is in thermal contact with the first resistor. A comparator is connected to the middle points of the Wheatstone bridge circuit thus formed. Relay operating means is provided to open the relay contacts when an output signal is produced by the comparator indicating that the glow plug temperature is sufficiently high. On-off cycling of the current flow to the glow plug is continued until the engine is ready to start.

Abstract: An electrical starting system for a Diesel engine has a manual selector switch which is moved momentarily to a preheating position to energize a relay which is then held energized by a relay switch from a battery D.C. source until the engine combustion chambers have been preheated sufficiently by preheating plugs to enable starting to be effected, indicated by the switching off of an indicator lamp. Starting can then be effected by the selector switch. If the preheating of the engine is incomplete the indicator lamp remains lit. A thermometric cut-out switch inhibits the preheating relay when the engine reaches a threshold temperature, avoiding wasteful operation of the preheating plugs with a hot engine.

Abstract: A monitoring circuit for electrically conductive resistive devices such as diesel glow plugs in which the devices are fed through an electrically sensitive path, and the voltage across the electrical devices is sensed with respect to a reference. If the sensed voltage is above the reference indicating the presence of a defective device, a warning is indicated. The circuit includes means allowing warm up of the devices before sensing, and for inhibiting signals, which would otherwise indicate a false warning, after a chosen period for sensing.

Abstract: Control apparatus for glow plugs provided for a diesel engine having a control circuit arrangment for controlling the supply of an electric current from a battery to the glow plugs in response to the temperature condition of the diesel engine. When the engine is cold, the supply of the electric current lasts until a predetermined temperature of the glow plugs is attained. After attainment of the predetermined temperature of the glow plugs, a low level electric voltage is applied to the glow plugs so as the maintain the predetermined temperature thereof. When the engine is warmed up, the supply of an electric heating current to the glow plugs is commenced at the same time as the starting operation of the diesel engine.

Abstract: To positively exclude oxygen from a heating spiral located within the interior of a glow plug, so that the heating spiral can use a material having a high positive temperature coefficient of resistance, an insulating bushing separates a central connecting bolt from the surrounding metal sleeve and at least one, and preferably both the bolt and the metal sleeve are formed with circumferential matching ridges and grooves into which the insulating bushing will be pressed to provide an effective seal and a long, tortuous path for any possible leakage of air past the seal, even under the extremes of operating conditions and temperature gradients to which glow plugs are exposed in use. To further exclude oxygen from the heating spiral, the filler material adjacent the sealing bushing can include material having a high affinity to oxygen, such as aluminum or magnesium, so that any oxygen molecules which might leak past the seal will be bound thereby.

Abstract: For use in a swirl-producing recombustion chamber of a Diesel engine, a glow plug comprises a shell which can be screwed into an engine block so as not to protrude into the precombustion chamber and a cylindrically shaped heating head attached to a plunger which is received in the shell and can be electromagnetically or hydraulically moved relative to the fixed shell. The heating head can be protruded from the shell so as to extend into a central region of the precombustion chamber when preheating of air is necessary but, at other times, can be retracted almost entirely into the shell so as not to obstruct violent swirling of air in the precombustion chamber.

Abstract: A starting aid for a combustion engine comprises a hollow elongated body and a refractory electrical heating element mounted in the body at one end thereof. Formed in said one end of the body are one or more holes through which, in use, the heating element can be exposed to the combustion mixture of an engine. In addition, the body is formed with at least one exhaust aperture which is spaced from the heating element in the direction of the other end of the body and which permits the escape of gases entering the body through said one or more holes. Extending through the body and electrically connected to the heating element is an electrode rod for supplying heating current to the heating element to raise its temperature. The electrode rod includes two relatively movable parts which are mechanically connected by resilient means to maintain the heating element in compression against said one end of the body and which are electrically connected by a flexible braid.

Abstract: To heat the glow plug for an internal combustion engine, a spiral band or ribbon is wound in an essentially co-planar spiral about a central bolt secured to the bottom of the glow plug, the outer terminal of the spiral being connected to a lead-in with highly positive temperature coefficient of resistance to provide for self-limiting current flow upon heating of the glow plug. All free spaces in the glow plug are filled with a highly heat-conductive insulating material, for example magnesium oxide.

Abstract: An ignition device for a rotary piston engine includes a glow plug which is mounted at an ignition port formed in an engine housing to communicate with a combustion and operation chamber and which, when electrically powered, is heated to red hot to ignite an air-fuel mixture in the combustion and operation chamber. The glow plug ignites the air-fuel mixture through a communicating port which is formed to face the combustion and operation chamber and which has a smaller aperture area than the cross-section area of the ignition port.

Abstract: To prevent damage to the heating wire of an electrically heated glow plug due to non-uniform expansion of materials within the glow plug upon heating thereof, and particularly due to excessive expansion of filler material surrounding a spiraled heating wire, the filler material is made in two sections, one being located within the spiral of the heater wire and comprising a material of a thermal conductivity of expansion approximately matching that of the heater wire, typically high-temperature annealed aluminum oxide, magnesium aluminum spinel, silicon nitride, boron nitride, silicon carbide, or the like, the outer section between the heater wire and the inner wall of the glow tube being of a material of good heat conductivity, such as magnesium oxide.

Abstract: A glow plug is maintained at a desired operating temperature by using as its heat generating element a material which may be quickly heated, has a non-zero resistance-temperature coefficient and has a repeatable resistance value at the desired operating temperature. The heat generating element is used as one leg of a bridge circuit and when the bridge is balanced, the engine starter is energized and a short time later the current through the bridge is interrupted.

Abstract: A glow plug or plugs for a Diesel engine is energized directly or indirectly through the normally closed contacts of a thermally operated switch, preferably a bimetal switch, in thermal communication with the engine and a local electric heater that is energized by the same source as the glow plug and controlled in unison with the glow plug. The bimetal switch is arranged to switch off at a temperature of the order of 80.degree. C. which, at an initial engine temperature of the order of -18.degree. C., permits the glow plug to heat to the order of 900.degree. C. The hysteresis in the bimetal switch is arranged to close the switch when the glow plug has cooled to the order of 810.degree. C., thus the glow plug is cycled between the order of 800.degree. C. and 900.degree. C. It has been found that the glow plug temperature rise at elevated temperatures is substantially less than proportional to heat input.

Abstract: An ignition system for rotary piston engines includes a glow plug in addition to the normal leading spark plug and trailing spark plug. The glow plug is mounted in the housing of the engine on the leading side with respect to the trochoidal minor axis in the direction of the rotor rotation and performs continuous ignition of the mixture during low speed and load operation of the engine. Thus, during the low speed and load operation the glow plug performs ignition in place of the leading spark plug whereas during other engine operating conditions the leading spark plug and the trailing spark plug perform the ignition of the mixture.

Abstract: An ignition system for rotary piston engine wherein a glow plug mounted in the epitrochoidal housing of the engine is supplied with electric power to maintain the surface temperature of the glow plug within a range from 900.degree. to 1100.degree. C. A control unit for controlling the supply of electric power to the glow plug produces an output pulse signal the pulse width thereof being varied depending on engine operating conditions such as the amount of fuel supply and engine rotational speeds. A power circuit receives the pulse signal from the control unit and on-off controls the supply of electric power to the plug from a battery.

Abstract: A glow plug for rotary piston engines adapted to be mounted in an engine plug hole so as not to project from the plug hole and to be traversed by a flow of fuel-air mixture temporarily trapped in the plug hole. The plug includes an elongated protective tube providing a straight root portion by which it is supported from a plug housing adapted to be inserted in a plug hole. The tube terminates in a closed end hook-shaped free tip portion spaced from the root portion and plug housing and lying in the same plane as the root portion. A helical heater coil is disposed in the protective tube with the pitch of the coil being smaller at the free tip portion than at the root portion so that greater heat is generated in the free tip portion than in the root portion.

Abstract: A sheathed electric heater for use as an engine glow plug or the like is formed by providing a closed end metal sheath with a diameter larger than the finished diameter, Installing in the sheath a centered electric heating element having an enlarged diameter portion that engages the sheath adjacent to its closed end, the sheath and heating element being formed of compatible metals capable of being welded together by cold working, filling the sheath interior around the element with granular electrical insulating material, and swaging the assembly to reduce its diameter, extend its length, compact the insulation and cold work the engaged end portions of the sheath and heating coil so as to increase their engagement pressure and thereby establish a low resistance electrical connection between them.

Abstract: An ignition aid for internal combustion engines includes a sintered refractory ceramic composite heating element having a high resistance central portion interposed between a low resistance terminal end portions. The heating element is positioned in a hollow electrically conductive body adapted to be removably inserted in an aperture in an engine. The heating element is disposed between and has its terminal end portions in electrical non-point contact with a bridge portion at one end of the hollow body and an electrode rod extending into the hollow body in sealed relation therewith. In one embodiment, the electrode rod comprises a pair of relatively movable parts, one of which is resiliently biased into engagement with the heating element by a resilient PTC resistance element electrically connecting the parts. In another embodiment, the heating element terminal portions are diffusion bonded to the electrode rod and bridge portion, respectively.

Abstract: In a glow plug igniter of the type used in internal combustion engines, having a hollow cylindrical casing and a central pin-terminal, a substantially flat-spiral-coiled, flexible resistance element, oriented perpendicularly to said pin-terminal with one end electrically connected to the casing and the other to the pin-terminal, is positioned at a nose end of the casing and spaced from but close to a backing seal of temperature and corrosion-resistant material. At least one seal hermetically closes the hollow casing. Preferably, spaced glass seals constitute the sole means for mounting the pin in the body.

Abstract: In a glow plug igniter of the type used in internal combustion engines, having a hollow cylindrical casing and a central pin-terminal, a substantially flat-spiral-coiled resistance element, flexible in a direction out of its plane, oriented perpendicularly to the pin-terminal with one end electrically connected to the casing and the other to the pin-terminal, is positioned at a nose end of the casing and spaced from a backing seal of temperature and corrosion-resistant, electrically insulating material hermetically closing the hollow casing. An idle bar of substantial width relative to the resistance element, bridges across the nose end of the casing, spaced from the resistance element. Preferably, the casing is crenellated, with opposed merlons, provided with weld projections, to which the ends of the idle bar are welded.